The catalytic hydrodesulfurization performance and mechanism of hierarchically porous iron-based catalyst for coal liquefaction oil

Hierarchically porous iron-based catalysts were prepared by impregnation and coprecipitation methods using carbon microsphere as a template. The catalytic hydrodesulfurization performance and mechanism of such catalysts for coal liquefaction oil were systematically characterized, especially by a gas chromatography atomic emission spectrometry (GC-AED). Results show that the as-prepared catalysts were highly dispersive nano-size particles (ca. 50 nm) with a large surface area (744.923 m(2).g(-1)). During the catalyst preparation, the carbon template might lead to the aggregation of FexOy with different stoichiometries. Therefore, the hierarchically porous iron-based catalysts were with mixed-valence and vacancy as active sites. Particularly, catalysts prepared under nitrogen atmosphere were found with a certain nitrogen doping to form Fe-N and/or Fe-CN. It could offer more active sites and lower the C-S bond strength, thus improve the desulphurization activity. In addition, the hierarchical pore structure could sufficiently adsorb hydrogen and sulfur-containing molecular to accelerate the mutual reaction among activated H radicals and S atoms. Consequently, the catalysts presented high efficiency and strong selectivity on the removal of sulfur heteroatom, even for the very stable thiophene and benzothiophene derivates. The conversion rates were achieved up to 100% and 74.23% for model compounds and coal liquefaction oil, respectively.